[PATCH 1/2] Prepare inet_pton to be fortified

[Florian Weimer]

* Aaron Merey:

> Split inet_pton internals such as __inet_pton_length from the
> inet_pton entry point.
>
> This allows the internals to be built with fortification while
> leaving the inet_pton entry point unchanged.
>
> Co-authored-by: Frédéric Bérat <fberat@redhat.com>

Looks good to me.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

We may want to change how we handle the fortify function body conflicts,
but this is a good interim measure.

Thanks,
Florian